Restraint System for a Motor Vehicle

ABSTRACT

The invention relates to a restraint system for a motor vehicle that is formed by one or several supporting structures, wherein the longitudinal extension of a supporting structure in the active state substantially exceeds the dimensions of the transverse extension and the supporting structure unfolds mainly in the direction of its longitudinal extension. So as to improve the restraint system such that the variables of the restraint system are adapted to the respective load, it is suggested that, during unfolding, the supporting structure ( 7, 8, 9 ), when impacting upon an obstacle ( 5 ), does not have the same stability as when it is completely unfolded, and/or does not reach the final volume or the final extension.

The invention relates to a restraint system for a motor vehicle according to the preamble of claim 1.

It is well known from safety features for motor vehicles to protect occupants from injuries by inflating an air bag in a short period of time which catches the occupant who is displaced in a forward direction.

It is thereby of interest that the air bag quickly reaches its effective volume. For this, it is necessary to produce relative large amounts of gas, e.g. in a pyrotechnical manner and to introduce them into the gas bag. With the dimensionig of the gas volume to be added, occupant/and or vehicle parameters have been evaluated recently, so as not to unfold the gas bag to its full size for example with a so-called “out of position” of the occupant. The adjustment to all possible load conditions and the relative cost-intensive control and regulation technique herefore is problematic.

Intensified efforts are made therefore to develop so-called self-regulating systems which can adjust automatically to the corresponding load conditions. The state of the art thereby shows for example venting apertures which close automatically when the inner pressure of the gas bag becomes too large.

From the German published application 2 302 737 is known a restraint system comprising a two-layer gas bag where the gas is only guided between the two layers, so that a complete gas cushion does not result, but a spherical annular supporting structure. The unfolding of the support structure thereby occurs in the transverse direction of the abutting gas cushions.

EP 0589 059 B1 shows furthermore, that it is necessary during the unfolding of the two-layer gas bag, to suck ambient air into the interior so as to overcome the negative pressure.

Both have in common that less gas volume is necessary to unfold the gas bag to its full size, due to the gas bag being formed with two layers. The temperature and the pollution can thereby be reduced.

Finally, GB 1 420 226 A shows a restraint system for a motor vehicle, where a tubular supporting structure is provided in the interior of the two-layer gas cushion, the longitudinal extension of which exceeds the dimensions of the transverse extension in the inflated, that is, active state. The supporting structure unfolds due to its particular geometry mainly in the direction of its longitudinal extension.

An automatic adjustment of the gas bag in dependence on the respective load condition, e.g. in dependence on the respective occupant or the respective occupant position is not described.

It is therefore the object to improve the generic restraint system in such a manner that the size of the restraint system adjusts to the respective load condition.

This object is solved according to the invention with the characteristics of claim 1. Advantageous developments result from the dependent claims.

A restraint system is suggested which does not achieve the stability it would have when fully unfolded and/or the final volume or the final extension during impacting upon an obstacle during the unfolding due to the particular geometric form of the supporting structure, that is, due to a longitudinal extension exceeding the cross section. The supporting structure has a different stability during the unfolding due to its longitudinal formation. While the supporting structure is initially rather unstable, that is, can be easily hindered during unfolding, the completely unfolded supporting structure achieves full stability, that is restraining force. This means that, if the supporting structure impacts upon an obstacle during the unfolding, as is the case for example with occupants leaning forward (out of position), the unfolding can be stopped easier or deflected due to the supporting structure which is still unstable. These small forces effect a low pressurization of the occupant.

If a supporting structure is mentioned in connection with the invention, a structure similar to a skeleton is meant—in contrast to a conventional spherical gas bubble (gas bag), which structure comprises a restraint effect in the fully unfolded state comparable to the conventional gas bag, but a substantially more complex structure, for example a branched tree structure. Thereby, not only the necessary gas volume can be reduced, but also the force peaks acting on the occupant during unfolding, if he is effectively “in the way” of the unfolding supporting structure. In contrast, the gas amount in the gas bubble is on a substantially higher level from the start of the activation until the full unfolding, so that obstacles in the unfolding path are put under more pressure independent of the unfolding state.

The supporting structure can preferably be filled with gas, whereby it is insignficant if it is filled with gas generated in a pyrotechnical manner or with gas from a pressure vessel or the ambient air. The ambient air can be guided into the carrier volume enclosed by the supporting structure by suction through the negative pressure occurring during the unfolding. The gas volume can be reduced further in this manner.

If several supporting structures are provided, which are connected to one another or to the environment in a fluidic manner, a restraint system can be formed, which is constructed in a net-like, tree-like or supporting frame-like manner. Thus, supporting structures proceeding in the longitudinal direction of the vehicle can be connected to supporting structures proceeding transversely to the transverse direction of the vehicle. The unfolding of the transverse supporting structures thereby nevertheless takes place in the direction of the longitudinal extension of the respective supporting structure.

The supporting structures can alternatively be connected by flexible sheets, in particular flexible textile sheets. If this is the case, the flexible sheet can be fixed between two adjacent supporting structures.

If several supporting structures are connected to one another by a flexible sheet, the gas can be used for restraining action in the carrier volume enclosed thereby. The gas in the carrier volume serving for the restraint of occupants can be heated or supplemented by means of a heating device (e.g. an ignition tablet or a small gas generator step, which develops heat with a possibly very low gas volume). The gas volume or the inner pressure and thus the restraint action increases therewith correspondingly.

If a supporting structure impacts upon an obstacle during unfolding, the gas flowing into the supporting structure can be distributed to other adjacent supporting structures or into the environment with the aid of redistribution means. It is also feasible that the inner pressure generated by the flow in the supporting structure is reduced by an increase of the cross section. This can take place in such a manner that tear seams break down at a certain pressure, so that the supporting structure can increase in its transverse direction. A pressure-relief valve is also conceivable, which opens when an interior pressure is reached which is too high.

With conventional compact gas bags, it was previously refrained from directing venting apertures towards the occupant, as gas temperatures are reached which are too high. As cold ambient air flows within the carrier volume, and not a pyrotechnically produced gas, venting apertures can be directed towards the occupant by the reduced temperature. An adaptivity of the air bag dampening can thus be achieved for various environmental condittions, by sealing a venting aperture cross section between occupant and air bag.

Thus, this contact surface and thus the sealing with persons having a higher volume (and usually a higher weight) is larger, so that a stronger restraint action is achieved hereby. With more severe accidents, the contact surface and thus the restraint action is also increased by a stronger immersion of the occupant into the air bag. This principle also permits a variable air bag dampening for belted and unbelted occupants, as in the unbelted state, the occupant will be immersed into the air bag with less force.

If the venting apertures are formed as perforations, that is, many small apertures, as for example with a textile net, a projection area corresponding to the measurements of the occupant can be closed. The reproducibility of the results increases on average with many small venting apertures.

In a preferred embodiment, at least one of the supporting structures extends at least partially in an overlap of a hard structure, as for example a supporting column. It is also possible to provide a structure which unfolds between the occupants as an interaction bag.

So as to be able to manufacture a complex supporting structure with its inflatable components and the flexible sheets, the one-piece woven technique is recommended. This technique distinguishes itself in that, on one and the same device, a double layer can be manufactured for the inflatable structures, and one layer for the flexible sheets, or a three-dimensional structure can be woven.

In the following, advantageous embodiments of the invention are explained in more detail with the aid of the drawing.

It shows:

FIG. 1 a supporting structure shortly after activation of a gas generator,

FIG. 2 a the obstruction of the unfolding of the supporting structure according to FIG. 1 when impacting upon an obstacle,

FIG. 2 b evasion of the supporting structure according to FIG. 1 when impacting upon an obstacle,

FIG. 3 the supporting structure according to FIG. 1 in the fully unfolded condition,

FIG. 4 a restraint system with a complex supporting structure, and

FIG. 5 two supporting structures connected to one another by a flexible sheet.

FIGS. 1 to 3 show a supporting structure 1 in a schematic side view, which is rolled up in the deactivated state. Alternatively, a zigzag folding or other folding is possible.

As can be seen especially from FIG. 3, the length L of the supporting structure in the active state substantially exceeds the dimensions of the cross section Q. It is thereby insubstantial which form of cross section is shown by supporting structure 1.

If a gas generator assigned to the supporting structure 1 is activated, the abruptly generated gas G reaches the interior 3 of the supporting structure 1 formed by walls 2. The unfolding of the supporting structure in the direction of its longitudinal extension is effected thereby. As the gas G in the longitudinal supporting structure 1 can only spread from the back to the front, the portion 4 of the supporting structure which is still rolled up is displaced in the flow direction and unreels thereby.

If an obstacle 5 is present in the unfolding path, the portion 4 which is not yet unfolded, is disconnected due to the low cross section, so that no further gas G can flow in (see FIG. 2 a). The supporting structure 1 is markedly unstable in relation to interfering transverse forces in this state, so that the portion not yet unfolded is simply disconnected at the location designated as 6 when an obstacle is encountered. The supporting structure thereby does not achieves the stability which it would have when fully unfolded and/or the final volume or the final extension, so that the load values on the occupants are reduced substantially.

Depending on the impact angle between the obstacle 5 and the supporting structure 1, an evasion of the supporting structure can take place instead of the complete disconnection. FIG. 2 b). The supporting structure also does not achieve the stability which it would have when fully unfolded.

If however the supporting structure 1 is completely filled with gas (see FIG. 3), the full stability, that is, the full restraining effect is achieved.

FIG. 4 shows a restraint system which is formed from two supporting structures 7, 8 proceeding in the longitudinal direction of the vehicle and a supporting structure 9 proceeding in the transverse direction of the vehicle. The three supporting structures 7, 8, 9 are connected to one another in a fluidic manner, so that the supporting structure 7, 8 first unfolds after activation along its longitudinal extension, and then also the supporting structure 9 in its longitudinal extension. The occupant 10 virtually enclosed by the supporting structures 7, 8, 9 can also be protected against lateral forces by the arrangement with an inclined impact.

A flexible sheet 11 can be fixed between the supporting structures 7, 8, 9, so that an interior 12 is enclosed, for example with four supporting structures arranged in a funnel-shaped manner. The gas present in the interior 12 can be heated or supplemented by a heating device (e.g. an ignition tablet or a small gas generator step which develops heat with possibly a very low gas volume), so that the gas expands and the system becomes harder.

In FIG. 5, a second embodiment is shown, where the transverse supporting structure is missing.

The arrangement of the supporting structures in cooperation with the flexible sheets significantly depends on the position of the restraint system within the vehicle and the expected load conditions. Thus, the supporting frame-like arrangement for a lateral impact protection will be designed in a different manner due to spatial reasons than supporting structures for the frontal impact. It is however a fact that a plurality of positions can be achieved in the vehicle with the longitudinal supporting structures, which conventional gas bags cannot achieve due to the necessary gas volume. 

1. Restraint system for a motor vehicle which is formed by one or several supporting structures, wherein the longitudinal extension of a supporting structure in the active state substantially exceeds the dimensions of the transverse extension and the supporting structure unfolds mainly in the direction of its longitudinal extension, characterized in that the supporting structure (7, 8, 9), when impacting upon an obstacle (5) does not have the same stability as when it is completely unfolded, and/or does not reach the final volume or the final extension.
 2. Restraint system according to claim 1, characterized in that the supporting structure (7, 8, 9) can be filled with gas.
 3. Restraint system according to claim 2, characterized in that the supporting structure (7, 8, 9) can be filled with gas which is produced in a pyrotechnical manner.
 4. Restraint system according to claim 2 or 3, characterized in that the carrier volume limited by the supporting structure (7, 8, 9) can be filled by aspiring or enclosing ambient air.
 5. Restraint system according to one or several of the previous claims, characterized in that several supporting structures (7, 8, 9) are provided, which are connected to one another or to the environment in a fluidic manner.
 6. Restraint system according to one or several of the previous claims, characterized in that supporting structures (7, 8, 9) are provided, which are connected to one another by a flexible sheet (11), in particular a textile flexible sheet.
 7. Restraint system according to one or several of the previous claims, characterized in that a heating device is provided, in particular an ignition tablet or a small gas generator step, which heats or supplements the aspired or enclosed gas in the activated state of the supporting structures (7, 8, 9).
 8. Restraint system according to one or several of the previous claims, characterized in that redistribution means for distributing the excess gas are provided.
 9. Restraint system according to claim 8, characterized in that the redistribution means redirects the excess gas into an adjacent supporting structure (7, 8, 9).
 10. Restraint system according to claim 8, characterized in that the redistribution means effects an increase of the cross section of the supporting structure (7, 8, 9) when the interior pressure is too high.
 11. Restraint system according to claim 8, characterized in that the redistribution means is a pressure-relief valve, through which the excess gas escapes to the environment or to adjacent supporting structures (7, 8, 9).
 12. Restraint system according to one or several of the previous claims, characterized in that venting apertures are directed towards the occupant from the enclosed carrier volume, which are covered by the occupant displaced in a forward direction.
 13. Restraint system according to one or several of the previous claims, characterized in that the venting apertures are perforations or other passages, which are included in the material enclosing the carrier volume.
 14. Restraint system according to one or several of the previous claims, characterized in that one of the supporting structures (7, 8, 9) extends with an at least partial overlap of a hard structure of the motor vehicle, in particular a supporting column.
 15. Restraint system according to one or several of the previous claims, characterized in that at least one of the supporting structures (7, 8, 9) unfolds between the occupants as an interaction bag.
 16. Restraint system according to one or several of the previous claims, characterized in that the one or several supporting structures (7, 8, 9) and/or the flexible sheet is produced in a one-piece-woven technique. 